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In Reply to: RE: 6NIP & 6H30Interpretation of tube test results. posted by Jim McShane on January 30, 2016 at 15:35:24
It's not the best machine to try to learn to use if you're just starting out and it really bothers me that there have never been any software updates and the instructions to get it to work in computer mode are awful/wrong.If you haven't tried "Computer Mode" you really don't know what it can do. Good luck setting that up though!
Answering your question - these tubes don't look all that well matched to me at the voltage/current tested if that's critical and some don't seem to test that strong either although they may work ok.
Edits: 01/30/16Follow Ups:
Thanks Barry ,
I'm sorry to all that replied to this post , the test was not done at auto bias mode but done in fix bias mode. One of our sponsors advised me to at least repeat the test the tube for at least 3x in order for these tubes to warm up.
Mondial
AT1000 Standard tube warm up time counts down from 60 seconds. You'll get fairly consistent readings with a three minute warm up. Note both these tubes are dual section triodes, two section tubes in one device, so the AT will prompt you for the second set of measurements on the readout when you're done with testing the first section. You test/ match both sections for Mu and gm regardless of what tester you are using.Check out this site for tube matching and testing triodes as this really is very basic and helpful. Mu or gain is what the AT incorrectly calls emissions.
http://www.tubeaudiostore.com/tubmatdem.html
Despite all the technical stuff, you care about two readings, Mu & gm. If the separate readings for both sections of tubes and with other tubes match to within 10 % or so and the percentage of both readings is not much less than 80% of specification, you will be fine.
Alternatively rerun the tests with proper warmup time for both tubes sections for all your tubes in fixed bias mode post them and let the group tell you if they're ok.
Edits: 01/31/16 01/31/16
Hi Barry ,
I had a email exchange w/ Chris of Amplitrex and he told me w/ regards to the 6NIP & 6H30 it's better to test it in auto bias mode . His reason is because these tube were designed not only for audio amplifiers but for other applications as well.So their characteristics vary from specifications more than typical is for audio tubes .
Mondial
You can change settings from/to Fixed or Auto Bias in the "System Menu" when you turn on the power while holding the left arrow button and you scroll through to select it. Of course that's not explained in the Operations Manual until page 20 in Section 8.1!If you're just trying to test tubes to assure they are ok, I'd still use FIXED BIAS for reasons in the link provided by JAZZDude.
More of a problem is that these two tubes can operate over a wide range of plate voltages as Chris said. Scroll through the tube table screen. If you look closely, there are 2 test settings for the 6NIP and 3 for the 6H30. Note that the eP (plate voltage) and iP (plate current) are different for each test setting when you click on them. You can't duplicate the REF 610T circuit conditions without knowing its plate voltages for these 2 tubes. Of course, as noted elsewhere, a simple "Good" "Bad" tester won't either!
Maybe your dealer/tech knows the best settings? If not, I would just run the tests at the lowest plate voltages 6NIP-2 & 6H30-3 to be safe on FIXED BIAS and be done with it. Note that after the test is run, you have to push the down arrow to get the second section of the tube's measurements (RESULTS2). Remember, they are dual triodes.
This process gives an indication if the tubes are ok and how close they match - just look at % of specification for iP and Gm.
If the real experts here have better ideas on this, please chime in.
Edits: 02/01/16
Thanks Barry,
It seems that these Amplitrex tube tester are not for mere mortals like me. It seems it's a tool for electrical engineers or people who studied electronics for a long time . Thanks for the advice.
Mondial
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